Robot Arm Calibration for Load Lock Transfer Alignment
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Solution Overview
Problem
Electronics processing systems face challenges in accurately transferring substrates between stations due to system errors, misalignments, and positional inaccuracies, leading to incorrect orientation and positioning, which can result in reduced efficiency and increased damage to components.
Innovation Solution
A method and system for calibrating transfer sequences between stations using a calibration object, which determines characteristic error values to correct for misalignments and positional errors, ensuring accurate alignment and orientation of substrates through the use of kinematic coupling interfaces and fiducials, and recording these values for future alignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If robot arms transfer substrates between stations without calibration, then the transfer process is simple and quick, but positioning accuracy and orientation precision deteriorate due to system errors and misalignments
Solution Approach 1:
The calibration object is placed at a target orientation in a station before transfer to the aligner station. This preliminary positioning allows the system to measure and determine characteristic error values in advance, which are then used to correct positioning and orientation errors during actual substrate transfer operations
Solution Approach 2:
A calibration object serves as an intermediary between the robot arm transfer system and the aligner station. This calibration object with fiducials and kinematic coupling interfaces enables the measurement and determination of characteristic error values, acting as a mediator that facilitates accurate calibration without requiring direct measurement between the robot arm and the aligner station
2Measurement precision
If multiple alignment operations are performed to correct positioning errors, then positioning accuracy improves, but processing time increases and productivity decreases
Solution Approach 1:
Characteristic error values are determined and stored in advance through calibration operations. These pre-determined error values are then applied during substrate transfer to correct positioning and orientation errors, eliminating the need for multiple iterative alignment operations and thereby maintaining high productivity
Solution Approach 2:
The system uses characteristic error values obtained from calibration measurements as feedback to adjust and correct the positioning and orientation of substrates during transfer. This feedback mechanism enables single-pass accurate alignment without requiring multiple corrective alignment operations
3Measurement precision
If characteristic error values are determined and stored for each station, then alignment accuracy improves, but data storage requirements and system complexity increase
Solution Approach 1:
The calibration object with its fiducials and kinematic coupling interfaces serves as a reusable template or copy that can be used to determine characteristic error values for multiple different stations. This single calibration object can be transferred between stations to calibrate each one, eliminating the need for separate calibration artifacts for each station
Data Source
AI summary
A first robot arm places a calibration object into a load lock that separates a factory interface from a transfer chamber using a first taught position. A second robot arm retrieves the calibration object from the load lock using a second taught position. A controller determines, using a sensor, a first offset amount between a calibration object center of the calibration object and a pocket center of the second robot arm. The controller determines a characteristic error value that represents a misalignment between the first taught position of the first robot arm and the second taught position of the second robot arm based on the first offset amount. The first robot arm or the second robot arm uses the first characteristic error value to compensate for the misalignment for objects transferred between the first robot arm and the second robot arm via the load lock.